The questionnaires evaluating functional status, disease activity and global status of patients with ankylosing spondylitis were translated into Czech language. These included Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Functional Index (BASFI) and Bath Ankylosing Spondylitis Disease – Global Score (BAS-G). The translation of each questionnaire was discussed, adapted to local conditions, then retranslated and compared with original version. The final Czech versions have been tested for their reliability and validity in a group of patients with AS who were indicated to balneotherapy in Jáchymov spa. The evaluation of questionnaires BAS-G, BASDAI and BASFI demonstrated high and sufficient value of reliability and validity for the total score as well as for its particularcomponents.Highcongruence in serialandquantitative correlation of both outcomes was demonstrated by reciprocal correlation analysis. Global assessment according to BAS-G score significantly correlated with the subjective status of patients and is fully in harmony with the general intent of the scale. Moreover, BASDAI significantly negatively correlated with Thomayer’s and fleche distances. BASFI score is an index mostly related to the objective status of AS, significantly correlates with all the distances and can be also used for all stages of the disease. Internal integrity of the Czech versions of questionnaires assessed by Cronbach coefficient alpha is 0.914 for BASDAI score and 0.929 for BASFI score. These values are very satisfactory and show high internal integrity of questionnaires. When balneotherapy has finished, the improvement in the assessment of questionnaires was demonstrated and relative improvement, near 25%, was expressed also in patients with stages II–III. In conclusion, Czech version of questionnaires BASDAI, BASFI and BAS-G for ankylosing spondylitis showed sufficient reliability and validity.

        Key words: ankylosing spondylitis, Bath Ankylosing Spondylitis Disease Activity Index (BASDAI), Bath Ankylosing Functional Index (BASFI), Bath Ankylosing Spondylitis – Global Score (BAS-G)